It is well know that dental implants, having a fixture part which is to be embedded into bone and an abutment part which is to be mounted on the tip of the fixture part, are used to fix dental protheses such as dentures or cast crowns. Conventional implants have a wide variety of geometrical forms and lengths. Conventional implants also have a singular structure which is to be inserted or embedded into bone and conventional implants can be divided into the categories of submerged type structures and non-submerged type structures depending on the means of their embedment. An implant for a non-submerged type structure has an abutment which is exposed in the oral cavity, while an implant for a submerged type structure has no such embedment initially, but will receive an abutment to be mounted after a certain period of time has passed from the operation or surgery during which the implant is embedded.
Conventional implants require a substantial amount of bone in which to be inlaid. If there is not a sufficient amount of bone in which to embed the implants, for instance, such as in the case of vertical bony defects wherein upper and lower alveolar bones have become atrophied by age, the patients are compelled to give up on having dental therapy with implants, unless the required amount of bone is transplanted.
On the other hand, the Distraction Osteogenesis Theory, first described in 1988 by G. A. Ilizarov, a Russian medical doctor, has attracted public attention as a medical method applicable to the treatment of malformation or such therapy against abnormal bone length. This osteogenetic method has produced good results for over 35 years in the correction of the form of the bone and the soft tissue. Although this technique has not as of yet been applied to any vertical bone augmentation, it is considered to be applicable not only to the orthopedic field, but also to the stomatognathic field, for example, to the improvement of the length, width, and radius of the lower jaw. This method has also been experimentally studied in Japan.
The idea of an augmented amount of bone to recover the bony form against substantial bone defect, malformation and atrophy has great medical possibilities. That is, this idea is based on the unique Distraction Osteogenesis Theory, which is in turn based on the concept that the continuous stimulating force has osteogenetic power and the capacity of mucous membrane expansion.
On the other hand, such an idea as osteogenesis has never been conceived up to now in any clinical studies or research of dental implants. The implant body has thus far been embedded only into a given bone.